Eating Well

By Marian Burros

Published: June 22, 1994

HO-HUM. Another month, another scare. The latest is about a possible connection between the high consumption of hot dogs and childhood leukemia.

But Americans appear to be so inured to the scare of the month that if the recent study in question has had any impact on hot dog sales, no one has noticed.

Twenty years ago, hot dogs were under fire along with bacon, ham and luncheon meats like bologna and salami. Their safety was in question because of the addition of a compound called sodium nitrite during the curing process. At the time, the topic was as hotly debated as bovine growth hormone in cows' milk is today.

Nitrites combine with substances called amines, found naturally in some foods and in the stomach, to form carcinogens called nitrosamines. Dr. William Lijinsky, former director of the Chemical Carcinogenisis Program at the Frederick Cancer Research and Development Center in Maryland, and an authority on nitrosamines, said that as far as he knew, nitrosamines were the most potent carcinogens yet discovered, and that they had caused cancer in every species of animal tested.

It is these same nitrosamines that researchers at the University of Southern California School of Medicine think might be the culprit in the higher incidence of leukemia among 232 children in Los Angeles. The researchers identified children under 10 who had developed leukemia and matched them with a control group of children who did not have the disease. The children with the highest incidence of leukemia surprisingly turned out to be the ones who regularly ate more than 12 hot dogs a month. But the group that ate hot dogs that frequently was small; 14 children with leukemia, and 3 who did not.

Two additional studies on hot dogs were published in June in the journal Cancer Causes and Control. But the studies showed either negligible risk or no risk at all.

Dr. Lijinsky found the California study intriguing, but said no conclusions could be drawn from it. "There seems to be a relationship, and the researchers seem to have considered the other factors, but there are only a very small number of cases," he said. "It's certainly well worth looking into."

Scientists generally agree that while the study was not definitive (nor was it reviewed by other experts), it still poses some troubling questions that deserve further examination.

But the public has either become jaded or extremely sophisticated. There are no mobs dumping hot dogs in the streets. Perhaps it is because the researchers themselves described their results as preliminary and because other experts pointed out how many other variables there were in such a study, which might account for the findings.

Dr. Michael Jacobson, executive director of the Center for Science in the Public Interest, a Washington-based advocacy group, was one of the first people to sound the alarm about nitrites in food in the 1970's. Although he described this newest study as very weak, he added: "A study like this cannot establish a cause and effect relationship, but it should not be dismissed entirely. Further studies should be done."

The press release that accompanied the study was very guarded. It said, "Our results, which are based on crude dietary histories, seem to indicate a possible association between processed meat consumption and childhood leukemia." The researchers called for further study.

The study revives questions that were raised 20 years ago about the safety of food cured with nitrites. In 1972, because of the pressure from consumer groups, the Department of Agriculture forced manufacturers to reduce levels of sodium nitrites in bacon from 200 parts per million to 120. Levels for sodium nitrites in other cured meats were left at 200 p.p.m., where they remain today. The agency also required the addition of ascorbic acid or a similar chemical to cured meats to reduce the formation of nitrosamines.

Since 1985, the Agriculture Department has had a proposal to reduce the level of sodium nitrite in bacon to 100 p.p.m., but nothing has come of it.

William Havlik, the acting assistant deputy administrator for science and technology in the Agriculture Department's Food Safety and Inspection Service, said that because the levels of nitrites in bacon had been lowered, nitrosamines were not found anymore when bacon was tested. But only 250 samples of bacon were tested by the agency in 1993.

When Dr. Lijinksy and others discovered in 1969 that nitrites formed nitrosamines, the processed meat industry was shaken. It responded by arguing that since nitrites could prevent the growth of Clostridium botulinum, which causes a potentially deadly form of paralysis, it was necessary to have sodium nitrites in these foods. But other companies produce products free of nitrites, and no one has died from eating them.

"The Complete Eater's Digest and Nutrition Scoreboard" by Dr. Jacobson (Anchor Press/Doubleday, 1985) said an alternative method for curing bacon was discovered that permits the use of as little as 40 p.p.m. of sodium nitrites. But the Agriculture Department has not forced the industry to adopt the new procedure, and a spokesman said the agency did not know if any bacon producers were using it.

The problem may not be as serious as it once was, because other curing techniques have been altered. At one time, both nitrites and nitrates were used in the curing process. Now only nitrites are used, and the process is more carefully controlled.

Nevertheless, there is a strong link between nitrosamines and cancer, and there is no set amount of nitrite consumption that is considered safe. In 1983, a study comparing the amount of nitrites consumed by various populations with the incidence of stomach cancer produced a striking correlation. The Japanese, who consume large amounts of nitrites, have the highest incidence of stomach cancer in the world. In the United States, the rate of stomach cancer has been declining for more than 50 years as the intake of nitrites has also been declining because of changes in the curing procedures.

The possibility that a high consumption of hot dogs may cause cancer in children is not the only reason they should not be consumed in large quantities. Traditional hot dogs are very high in fat, particularly saturated fat; chicken and turkey hot dogs have less fat, but the levels are still quite high. The same is true of all processed meats.

"Reduce consumption of them as much as you can," Dr. Lijinsky said. "They are a source of a possible cancer risk. I would not expose my children to it. It's like secondhand smoking. It adds to other risk factors we are already exposed to."